(i) Field of the Invention
The present invention relates to a residual chlorine meter which can measure a residual chlorine concentration in water such as tap water, water for a pool or industrial water easily.
(ii) Description of the Related Art
Water such as tap water, water for a pool or industrial water is chlorinated for the sake of sanitation. To keep a residual chlorine concentration resulting from the chlorination at an appropriate level, means for measuring the residual chlorine concentration has been disclosed.
For instance, a residual chlorine concentration measuring device disclosed in Patent Publication 1 comprises pH measuring means (pH meter) and electric conductivity measuring means (electric conductivity meter) and determines calibration factors corresponding to the measured pH and electric conductivity of sample water based on calibration curves associated with the pH dependency and electric conductivity dependency of an apparent residual chlorine concentration resulting from normalization of a true value of a residual chlorine concentration and calibrates the apparent residual chlorine concentration of the sample water based on the calibration factors so as to determine a true residual chlorine concentration. The device is means for measuring a residual chlorine concentration with excellent measurement accuracy.
Meanwhile, a residual chlorine concentration measuring method disclosed in Patent Publication 2 is a method using a phosphate buffer having a more alkaline pH than 6.5 together with a liquid DPD reagent. The method is capable of measuring a residual chlorine concentration without any problem.    Japanese Patent Laid-Open Publication No. 9-329577    Japanese Patent Laid-Open Publication No. 2003-215119    However, the residual chlorine concentration measuring device disclosed in Patent Publication 1 has a problem that since the device has generally expensive measuring means including the pH meter and the electric conductivity meter, the device as a whole becomes expensive accordingly. Meanwhile, the residual chlorine concentration measuring method disclosed in Patent Publication 2 has a problem that it requires a high running cost and is troublesome to use since it uses a liquid DPD reagent for every measurement.
Thus, in view of such conventional problems, an object of the present invention is to provide a residual chlorine meter capable of measuring a residual chlorine concentration inexpensively and easily.